Day 820

Wednesday.

1501.04650
Cool core bias in Sunyaev-Zel'dovich galaxy cluster surveys
Lin, McDonald, Benson, MIller

Estimate the effect on the observed SZ signal of centrally-peaked gas density profiles (cool cores) and radio emission from the BCG by creating mock observations of sample of clusters that span the observed range of classical cooling rates and radio luminosities.  Find that the inclusion of a cool core can cause a change in the measured SPT significant of a cluster between 0.01% - 10% at z>0.3, increasing with cuspiness of the cool core and angular size on the sky of the cluster (i.e., decreasing redshift, increasing mass).  Provide quantitative estimates of the bias in the SZ signal as a function of a gas density cushiness parameter, z, mass and the 1.4 GHz radio luminosity of the central AGN.  Based on this work, estimate that for the Phoenix cluster (one of the strongest cool cores known), the presence of a cool core is biasing the SZ significance high by ~6%.  The ubiquity of radio galaxies at the centers of cool core clusters will offset the cool core bias to varying degrees.

1501.04733
Improving the LSST dithering pattern and cadence for dark energy studies
Carroll, Gawiser, ... et al

LSST: observed the entire southern sky over 10 years starting in 2022 in 6 liters, grizzly, with unprecedented depth and time sampling.  Artificial power on the scale of 2.5 deg LSST FoV will contaminate measurements of BAO, which fall at the same angular scale at z~1.  Using the HEALPix framework, demonstrate the impact of an "un-dithered" sure, in which 17% of each LSST FoV is overlapped by neighboring observations, generating a honeycomb pattern of strongly varying survey depth and significant artificial power on BAO angular scales.  Find that adopting large dithers of amplitude close to the LSST FoV radius reduces artificial structure in the galaxy distribution by a factor of ~10.  Propose an observing strategy utilizing large dithers within the main survey and minimal dithers for the LSST Deep Driling Fields.  Show that applying various magnitude cutoffs can further increase survey uniformity.  Find that a magnitude cut of r<27.3 remove significant spurious power from the angular PS with a minimal reduction in the total number of observed galaxies over the ten-year LSST run . Also determine the effectiveness of the observing strategy for SNeIa and predict that the main survey will contribute ~100k SNeIa.  Propose a concentrated survey where LSST observes 1/3 of its main survey area each year, increasing the number of main survey SNeIa by a factor of ~1.5, while still enabling the successful pursuit of other science drivers.